Gerber Parameters - Decimal places not up to Ucamco standard

Question

In the Artwork Control Form (Export -> Gerber Parameters) at the General Parameters tab, the number of integer and decimal places for Gerber export are set in the Format box. It seems like I can set any number here, but the documentation says that the number needs to be between 0 and 5. Looking at the FS command line in the generated Gerber file, it seems like the documentation is right. Setting 6 decimals will only get you 5 decimals (%FSLAX45Y45*MOMM*%). 
 Anyhow, the problem is that the Gerber Layer Format Specification ( https://www.ucamco.com/files/downloads/file_en/416/the-gerber-layer-format-specification-revision-2021-02_en.pdf ) strongly suggest to use 6 decimals. 
 Page 47: 
 "Always use metric, with 6 decimals. 
 It is sometimes argued that 6 decimals is overkill as the PCB design grid is much coarser. This is not a valid argument. Many points in a Gerber file are calculated; intersections, certainly with circles, have rational or even irrational coordinates, resulting in rounding errors. Even small perturbations can turn an otherwise perfect arc into an invalid one or turn an impeccable contour in an invalid self-intersecting one. Most errors such as missing clearances have low resolution as root cause and are solved when metric 6 mm is set. There only downside to high resolution is that the file becomes about 5% bigger, which is not a reason to throw away precision and risk scrap. There is no reason to use antiquated imperial units. An underlying component or design grid may be imperial, but a nm unit expresses any imperial value of 1/100 mil or larger without rounding error &ndash; amply sufficient for PCBs. By using inch, which is 25.4 times larger than mm, one gives up precision for no gain" 
 What am I to think about this? Shouldn't a leading PCB CAD tool meet the Ucamco recommendations? 
 /F

JuanCR · Answer

Hi Fredda, 
 
 Concerning your notes on the way Gerneral Parameters work in Artwok generation, I think there is a slight misunderstanding. Let me first explain what I've found so you can correct me if I'm wrong: when going through the text of page 47, it seems as if the document is talking about Decimal places. They recommend it should be 6. Additionally, I've also read in page 46 that Integer places range from 1 to 6, but it depends on the size of the board and a typical value is 3. 
 
 Now, if you see the general parameters section of the Artwork Control Form:

When you select the Integer places, the range shown below is 0 - 5. And when you select the Decimal places, the range is now 0 - 6. Both parameters are within specs of Ucamco, and most importantly, the decimal one is. 
 
 So, let me know if there was a confusion about these numbers and how I can help you further. 
 
 The thread still stands as a valid discussion on the topic of which format is more popular. But I wanted to clraify this technical tool-specific aspect with you.

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Gerber Parameters - Decimal places not up to Ucamco standard

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